Magnetic clamp

ABSTRACT

A clamp for releasably holding sheet material includes a rigid base of nonmagnetic material and an elongated strip of flexible material. The base carries a permanent magnet at one end, and the elongated strip is attached to the other end of the base and carries a second permanent magnet overlying the permanent magnet in the base. A recess is formed in the base underlying the central portion of the strip in such a manner that, by depressing that portion of the strip, the magnets are caused to part permitting insertion or removal of a piece of sheet material.

United States Patent [72] Inventor [21 Appl. No. [22] Filed [45] Patented [73] Assignee [54] MAGNETIC CLAMP 87.8; 24/73. 151, 73 (Machine), 243 (P), 11 (T.D.), 252(PC), 255(FC), 259(FC) [56] References Cited UNITED STATES PATENTS 1,877,849 9/1932 Schmidt 16/87.8UX

2,601,424 6/1952 Baker 24/49M 3,097,406 7/1963 Yarborough 24/ 1 1X FOREIGN PATENTS 1,216,408 11/1959 France 16/872 407,444 8/ 1966 Switzerland 24/73. 15 1 Primary ExaminerDonald A. Griffin Attorneys-Robert W. Hampton and Milton S. Sales ABSTRACT: A clamp for releasably holding sheet material includes a rigid base of nonmagnetic material and an elongated strip of flexible material. The base carries a permanent magnet at one end, and the elongated strip is attached to the other end of the base and carries a second permanent magnet overlying the permanent magnet in the base. A recess is formed in the base underlying the central portion of the strip in such a manner that, by depressing that portion of the strip, the magnets are caused to part permitting insertion or removal of a piece of sheet material.

PATENTED m 4mm 7 3.577583 WILLA RD R. AMANN INVENTOR.

BY y/aj/W AT TORNE YS 1 MAGNETIC CLAMP BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates to holders for sheet material and more particularly to clamps for releasably holding sheet material by magnetic means.

2. Description of the Prior Art Clamps for releasably holding sheet material are well known and commonly employ spring devices which rely upon the spring force to secure the sheet. In devices of this type, the force of the spring must be sufficient to firmly grasp the workpiece. Since the spring force remains applied while the clamp is open, the operator is required to maintain opening pressure while the sheet material is being inserted or withdrawn. In order to require less opening pressure during operation, such devices are commonly provided with relatively long lever arms to produce sufficient mechanical advantage whereby the closing force of the spring can be overcome .with only slight effort. As a result, the travel length of the opening lever is great,

reducing the ease in which these devicesmay be operated with' one hand.

Other types of clamps known in the art employ magnetic means for holding sheet material. One such clamp of this type provides for the pivoting of a magnet about one comer thereof to open the clamp sufficiently to insert thesheet. This type of clamp generally requires less force to keep it open due to the fact that the closing force of the magnetrapidly decreases as the magnets are parted when the clamp is opened. Such a clamp is disclosed in US. Pat. No. 2,693,370 to John E. Wheatley entitled HOLDER FOR PAPER OR" THE LIKE which is directed to a clipboard-type clamp. The foregoing clamp includes a permanent magnethaving two faces in obtuse angular relationship permittingthe clamp to be rocked about the intersection of the faces to raise-one face from the clipboard surface, thereby permitting the insertion of a sheet of paper. The clamp is magnetically held .inthis open position until closing pressure is applied. While such a clamp serves its intended function of permitting.orie-handedoperation while the clipboard is resting on a surface, itwould not be suitable for similar one-handed use where the'entire structure ishand held since opening pressure is applied to one point and closing pressure is applied to another, resulting in the need to shift ones grip to close the clamp.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a clamp for sheet material which may be easily opened and closed with only one hand. It is another object of theinvention to provide a clamp which is closed by merely releasing the opening pressure. Still another object is to providea clamp which requires less force to keep it open than to initially open it.

In accordance with a preferred embodiment of the invention, a clamp includes an elongated base having a permanent magnet at one end, means for suspending it from a-track at the other end and a recess therebetween. Aflat strip of resilient material is carried by the base and spans the recess. A second permanent magnet attached to the strip overlies the'magnet in the base to securely hold a piece of sheet material placed between the magnets. One edge of the magnet attachedto the strip forms a fulcrum about whichithe magnet may be pivoted by depression of the strip in the region of the recess, permitting insertion or removal of a piece of sheet material; The clamp retums to its closed position when opening pressure is removed.

The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred em bodiment presented below.

BRIEF DESCRIPTION OF THE DRAWING In the detailed description of the preferred embodiment of the invention presented below, reference is made to the acco'mpanying drawing, in'which:

2 FIG. I is a perspective view showing the clamp of the present invention;

FIG. 2 is a perspective view showing the operation of the.

clamp shown in FIG. 1;

FIG. 3 is a segmental view of the clamp taken along line 3-3 of FIG. I; and

FIG. 4 is a fragmentary view showing the method of mounting the clamp shown in FIG. I. t f

PREFERRED EMBODIMENT OF THE INVENTION Referring to the drawings, there is shown a clamp I0 having material and a flexible body member 14 of nonmagnetic material such as plastic. Of course other suitable materials for base member 12 and body member 14 will readily occur to those skilled in the art.

Base 12 is formed with a recess 16 at one end into which a permanent magnet 18 is secured by suitable means. Another recess 20 is formed in the central region of base 12 adjacent magnet 18. The opposed end of base 12 is provided with an upstanding projection 22 and a suspension device 24 to be more fully described below.

One end of body member 14 is attached to upstanding projection 22 of base I2 by suitable means such as conventional canoe clips 26 and abuts a projection 27 provided for alignment purposes. The other end of body member 14 carries a spacer 28 of nonmagnetic material and a permanent magnet 30 overlying magnet 18. Spacer 28 is provided to prevent magnet 30 from attracting adjacent clamps of similar construction. The spacer may be bonded to body member 14 as shown or formed as an integral molding. Of course spacer 28 may be omitted in cases .where the clamp is not intended for use near other magnetic materials. As best seen in FIG. 3, magnet 30 is somewhat shorter than magnet 18 to provide a corner or fulcrum 32 about which it may be pivoted in a manner to be described. a

The suspension device shown generally at 24 is provided to cooperate with a track 34 as shown in FIG. 4. Track 34 has a generally semicylindrical lower portion 36 with a flat upper surface 38. A flange 40 extends from upper surface 38 and is supported by a plurality of brackets, one of which is shown at OPERATION In operation, clamp 10may be grasped withone hand. As shown in FIG. 2, finger depression of resilient body member 14 in the region of recess 20 causes attached magnet 30 to rotate about its rear corner 32, parting the bottom surface of that magnet from the top surface of magnet 18 sufficiently to pennit insertion of a piece of sheet material. Once the magnets are parted, only slight pressure is required to hold them apart since the attractive force of the magnets decreases as they separate.

After insertion of the sheet material, body member 14 is released and returns to its original configuration as shown in FIG. I, firmly clamping the sheet material between magnets 18 and 30. Clamp 10 can now be suspended from track 34 in the manner described above and stored or moved along to the next station. The sheet can be released in a similar manner by merely grasping the clamp in one hand and depressing body member 14 with a finger, or the sheet material can be pulled from between magnets 18 and 30 without depressing body member 14 or touching the suspended clamp. Of course, the loading and unloading may easily be carried out while the clamp is suspended from track 34.

As can beseen from the above description, the present in vention provides a clamp which may be 'readily held and opened with one hand and which may be held'open with only slight pressure. Further, the clamp may be closed simply by reference to the preferred embodiment thereof, but it will be understood that variations and modifications can be efiected within the spirit and scope of the invention. For instance, magnet 30 need not be shorter than magnet 18 as the corner of either magnet can form the fulcrum. lf magnet 30 were the same length as magnet 18, magnet 30 would slide over the comer of magnet 18, making that comer the fulcrum.

' lclaim:

l. A clamp adapted to ride on and travel along a suspended t'rackhaving a flat, horizontal support surface and a central, upstanding flange extending from the surface, said clamp comprising:

a. a base member defining an edge, there being a hole having an inner surface and extending through said base member, and there being a slot extending from said hole to the edge whereby said device may be suspended from the track with the inner surface of said hole resting on the horizontal surface of the track and with the flange of the track extending through said slot;

b. a body member overlying said base member and having opposed portions, one of said portions being connected to. said base member; and i c. magnetic means carried by said members for releasably holding the other of said portions to said base member.

2. Aclamp as defined in claim 1 wherein said body member is at least partially formed of resilient material.

-3. A clamp as defined in claim 1 wherein said inner surface I of said hole has an arcuate shape, whereby said clamp is suspended from said track with minimum frictional contact.

4. A clamp for releasably retaining a workpiece, said clamp comprising:

a base member; a body member at least partially formed of flexible material,

and overlying said base member and having opposed portions, one of said portions being connected to said base member; and

magnetic means carried by said base and body members for releasably holding the other of said portions to said base member to releasably retain a workpiece between said other portion and said base member;

wherein said base and body members define a space between said one portion and said magnetic means into which said body member can be flexed, and a fulcrum about which said other portion is pivotable in response to the flexing of said base member for separating said other portion from said base member to release a retained workpiece. v

5. A clamp as defined in claim 4 wherein:

a. said body member is a flat strip which can be flexed into said space; Y

b. said space is a recess located in said base member between said one portion and said magnetic means and adjacent said body member; and

c. said magnetic means includes a permanent magnet carried by said other po'rtionof said body member, said magnet having an edge which defines said fulcrum, whereby said body member can be flexed into said recess to cause said other portion to pivot about said'fulcrum to separate said other portion from said base.

6. A clamp for releasably retaining a workpiece, said clamp comprising: v 3

' a. a base member;

. b. a movable body member resiliently coupled to said base member; and

c. means earned-by said members for exerting a magnetic force urging said body member in a first direction against said base member for releasably retaining the workpiece between said body member and said base member,

d. said body member being movable against the force of said magnetic means in a second direction substantially opposite to said first direction to separate at least a portion of said body member from said base member.

7. A clamp as defined in claim 6 wherein:

a. said body member has opposed portions;

b. said magnetic means releasably holds one of said portions against said base member; and

c. one of said members includes a fulcrum about which at least a section of said body member is adapted to pivot to move said one portion from said base member in said second direction against the force of said magnetic means.

8. A clamp as defined in claim 6 wherein:

a. said body member is at least partially formed of resilient material and has opposed portions;

b. said magnetic means releasably holds one of said portions to said base member; and

c. one of said members includes a fulcrum about which at least a section of said body member is adapted to pivot to move said one portion from said base member in said second direction against the force of said magnetic means.

9. A clamp as defined in claim 6 wherein:

a. said body member has opposed portions;

b. said magnetic means releasably holds one of said portions against said base member;

c. one of said members includes a fulcrum about which at least a section of said body member is adapted to pivot to move said one portion from said base member against the force of said magnetic means; and

d. said base member has an edge and is adapted to ride on and travel along a suspended track having a flat, horizontal clamp-supporting surface and a central, upstanding flange extending from the surface, said clamp further comprising:

1. a hole defined by said base member, said hole having an inner surface and extending through said base member, and

2. a slot defined by said base member and extending from said hole to the edge of said base member, whereby said clamp may be suspended from the track with the inner surface of said hole resting on the surface of the track and with the flange of the track extending through said slot. 

1. A clamp adapted to ride on and travel along a suspended track having a flat, horizontal support surface and a central, upstanding flange extending from the surface, said clamp comprising: a. a base member defining an edge, there being a hole having an inner surface and extending through said base member, and there being a slot extending from said hole to the edge whereby said device may be suspended from the track with the inner surface of said hole resting on the horizontal surface of the track and with the flange of the track extending through said slot; b. a body member overlying said base member and having opposed portions, one of said portions being connected to said base member; and c. magnetic means carried by said members for releasably holding the other of said portions to said base member.
 2. A clamp as defined in claim 1 wherein said body member is at least partially formed of resilient material.
 2. a slot defined by said base member and extending from said hole to the edge of said base member, whereby said clamp may be suspended from the track with the inner surface of said hole resting on the surface of the track and with the flange of the track extending through said slot.
 3. A clamp as defined in claim 1 wherein said inner surface of said hole has an arcuate shape, whereby said clamp is suspended from said track with minimum frictional contact.
 4. A clamp for releasably retaining a workpiece, said clamp comprising: a base member; a body member at least partially formed of flexible material, and overlying said base member and having opposed portions, one of said portions being connected to said base member; and magnetic means carried by said base and body members for releasably holding the other of said portions to said base member to releasably retain a workpiece between said other portion and said base member; wherein said base and body members define a space between said one portion and said magnetic means into which said body member can be flexed, and a fulcrum about which said other portion is pivotable in response to the flexing of said base member for separating said other portion from said base member to release a retained workpiece.
 5. A clamp as defined in claim 4 wherein: a. said body member is a flat strip which can be flexed into said space; b. said space is a recess located in said base member between said one portion and said magnetic means and adjacent said body member; and c. said magnetic means includes a permanent magneT carried by said other portion of said body member, said magnet having an edge which defines said fulcrum, whereby said body member can be flexed into said recess to cause said other portion to pivot about said fulcrum to separate said other portion from said base.
 6. A clamp for releasably retaining a workpiece, said clamp comprising: a. a base member; b. a movable body member resiliently coupled to said base member; and c. means carried by said members for exerting a magnetic force urging said body member in a first direction against said base member for releasably retaining the workpiece between said body member and said base member, d. said body member being movable against the force of said magnetic means in a second direction substantially opposite to said first direction to separate at least a portion of said body member from said base member.
 7. A clamp as defined in claim 6 wherein: a. said body member has opposed portions; b. said magnetic means releasably holds one of said portions against said base member; and c. one of said members includes a fulcrum about which at least a section of said body member is adapted to pivot to move said one portion from said base member in said second direction against the force of said magnetic means.
 8. A clamp as defined in claim 6 wherein: a. said body member is at least partially formed of resilient material and has opposed portions; b. said magnetic means releasably holds one of said portions to said base member; and c. one of said members includes a fulcrum about which at least a section of said body member is adapted to pivot to move said one portion from said base member in said second direction against the force of said magnetic means.
 9. A clamp as defined in claim 6 wherein: a. said body member has opposed portions; b. said magnetic means releasably holds one of said portions against said base member; c. one of said members includes a fulcrum about which at least a section of said body member is adapted to pivot to move said one portion from said base member against the force of said magnetic means; and d. said base member has an edge and is adapted to ride on and travel along a suspended track having a flat, horizontal clamp-supporting surface and a central, upstanding flange extending from the surface, said clamp further comprising: 